High molecular weight HDPE plastic

High molecular weight HDPE is increasingly being used for drums, pails, totes, and similar shipping containers, as an alternative to steel and fiherboard. Plastic drums are often used for chemicals, and are also used frequently in the food-processing industry. Standard drum sizes in North America are 57, 76, 114, 132, 208, and... 

W.D. Heitz, Paraloid extrusion aids for high molecular weight hdpe film resins, US Patent 4963622, assigned to Union Carbide c3remicals and Plastics Company Inc. (Danbury, CT), October 16,1990. 

Plastics are families of materials each with their own special advantages. An example is polyethylene (PE) with its many types include low density PE (LDPE), high density PE (HDPE), High molecular weight PE (HMWPE), etc. The major consideration for a designer and/or fabricator is to analyze what is required as regards to product performances and develop a logical selection procedure from what is available. 

Major markets for LDPE are in packaging and sheeting, whereas HDPE is used mainly in blow-molded products (milk bottles, household and cosmetic bottles, fuel tanks), and in pipe, wire, and cable applications. Ultra-high-molecular-weight polyethylene materials (see later), which are the toughest of plastics, are doing an unusual job in the textile machinery field. 

Although some polymers may be satisfactory when used under the stress of static loads, they may fail when subjected to impact. The impact resistance, or resistance to brittle fracture, is a function of the molecular weight of a polymer. Thus uhmwpe is much more resistant to impact failure than general purpose high-density polyethylene (hdpe). The impact resistance of brittle polymers is also increased by the addition of plasticizers. Thus polyvinyl chloride (PVC), plasticized by relatively large amounts of dioctyl phthalate, is much less brittle than unplasticized rigid PVC. 

The SSE process based on changes in polymer-billet shape is, first of all, characterized by the EDR value. The limited EDR value is determined by polymer type, molecular weight and morphology. For example, for HDPE it may reach more than 40 (1). For polyoxymethylene (POM), polypropylene (PP), PTFE the maximum values of draw ratio equal 10,6, and 4 (20-22), respectively. For polymethylmethacrylate (PMMA), polystyrene (PS), polycarbonate (PC), and other amorphous polymers they are even lower (21,23). The extruded specimens are highly oriented and possess improved mechanical properties. In the case of semicrystalline polymers, the extrusion results in a considerable increase of tensile modulus and strength (1,2). With amorphous polymers, a considerable increase of plasticity is observed alongside with increase of tensile moduli (21,23). 

---